1. The Field of the Invention
The present invention relates to kayaks. More specifically, the present invention relates to an open cockpit kayak having inflatable (or air filled) sections forming sections of the upper surface of the kayak.
2. State of the Art
Kayaks are available in various different designs, such as closed cockpit and open cockpit designs. FIG. 1 shows a typical whitewater kayak 10. When referring to whitewater kayaks 10, we refer to a boat which has a design optimized for whitewater navigation. Whitewater kayaks 10 are typically of rotomolded plastic or composite construction, and the user typically sits inside the hull of the kayak such that the kayak encloses the legs of the user. The user typically wears a spray skirt 26 made of neoprene, nylon or similar material which surrounds the user's torso and is affixed around the coaming 22 (a raised rim) of the kayak cockpit 18 to seal out water.
The upper surface 14 of a closed cockpit kayak 10 is enclosed except for a cockpit opening 18 at the seat. The user sits in the kayak hull with their legs enclosed within the kayak 10 and their torso extending from the opening 18 in the upper surface 14. Whitewater kayaks 10 are highly maneuverable kayaks, and the enclosed upper surface 14 allows a person to roll the kayak more easily if inverted in the water.
Whitewater kayaks 10, however, require additional skill as a person can not exit the kayak easily and quickly in case of an emergency. The failure to exit a whitewater kayak 10 in the event of being pinned against an obstacle, broaching, or the failure to roll upright can result in serious injury and/or death. In order to exit a whitewater kayak 10, the user must have a free hand to pull the grab-loop of his/her spray skirt 26 to remove the spray skirt. The user may not always have a free hand available, especially if the user is already using both hands to steady themselves or keep their head above water. It is also possible for a kayaker to be stuck in a position which does not give them immediate access to the grab-loop, such as having their torso pinned against the stern deck. Should removal of the skirt 26 prove to be impossible, exit can be extremely difficult.
Egress of a whitewater kayak 10 typically requires: 1) a free hand to pull the spray skirt grab-loop, 2) removal of the spray skirt 26, 3) removal of the user's lower limbs from within the kayak hull, 4) the user having “clean” gear (such as bare feet, socks or booties that don't have laces, straps, buckles, etc.) that won't get caught on foot pegs, outfitting or hardware inside the kayak 10 and thus prevent the user from exiting the kayak.
Egress typically results in the flooding/swamping of the kayak 10 and an increased weight/momentum/wetted surface area of the kayak which increase the hazards and difficulties associated with recovery of the kayak in moving water. A swamped kayak as such also poses greater danger to those downstream from it in moving water.
Even when a kayaker is successful at exiting the kayak 10, further complications arise, such as the kayak filling with water which must be drained in order for the kayak to be operable again. This generally requires the recovery of the kayak 10 which can be difficult since such swamped kayaks tend to be much heavier than un-swamped kayaks. A swamped kayak 10 is also more likely to become pinned on rocks and require mechanical advantage to un-pin. An additional hazard is posed by the increased weight and momentum of a swamped kayak 10, as the kayak can be dangerous if the user is downstream of the swamped kayak and becomes caught between the kayak and a rock or obstruction in the river.
After egress a user must typically perform the following steps required to resume paddling and use of the kayak 10: 1) the kayak 10 must be recovered, possibly requiring a high degree of strength or leverage to un-pin the kayak, 2) the kayak must be drained, generally requiring a somewhat dry, level surface, and 3) the user must re-enter the kayak and re-secure the spray skirt 26, which is also fairly difficult without access to a dry, level surface.
Unintentional egress of the kayak 10 can also be caused by the failure of the spray skirt 26 when water pressure builds on it in areas such as the base of waterfalls. Water pressure may build on the skirt 26 to the point where it fails, forcing unintentional egress. This typically happens in jump hydraulics (commonly referred to as “holes”), upon landing from waterfalls or any situation where sufficient pressure forms on the skirt 26.
Because of the confined nature of typical whitewater kayak 10 designs, special low-profile gear must be used on the feet and legs which avoids shoelaces, straps, buckles and other loose components which might get caught in the internal outfitting of the kayak and thus prevent the kayaker from exiting. Such gear, while a necessity for safe use of the kayak 10, is usually poorly suited to hiking and traversing the rocky and rough terrain which is typically found around whitewater rivers, and recovery of the kayak 10 typically requires such hiking. After the kayak 10 has been recovered, it must be drained of water which typically requires moving the kayak to the river bank to provide a solid surface on which to manipulate the boat. Some rivers do not always have easily accessible banks either due to the extreme width of the river, the steep angle of the banks (such as sheer canyon walls), heavy vegetation overgrowth, etc.
Kayaks 10 pose additional dangers. A person can easily hit their head or body on the rigid upper surface 14 of the kayak 10 as they reenter the water after passing over a waterfall or are otherwise tossed about by the water or as they bump into the rocks. Whitewater kayaking involves the navigation of rivers and streams with high gradient, occasionally requiring the user to cross waterfalls, ledges and other drops which involve a period of freefall and subsequent impact upon landing. The whitewater kayak 10 does little to absorb or transfer the energy produced in such drops away from the boater. Injuries commonly result from these impacts in the form of broken ankles, legs and other bodily harm resulting from the full weight and momentum of the kayaker being transferred to the lower limbs.
Additionally, the upper body is subject to injuries resulting in the abrupt impact with the hard plastic deck or cockpit coaming 22. Injuries typical to such impact include broken ribs, broken nose, jaw and tooth injuries, concussion, broken back, etc. If a person goes over a waterfall in a kayak, the kayak points downwardly as it enters the water, often causing the person to hit their head or body on the upper kayak surface 14 as the kayak reenters the water and decelerates from the drop. The person may also injure their feet, legs, and lower body as the force of impact is transferred through the kayak 10 without mitigation. A person may also become trapped in a kayak if the kayak shell becomes collapsed due to water pressure, a collision with a rock, etc.
The inclusion of the cockpit opening 18 in a whitewater kayak 10 poses a structural problem, as it reduces the structural rigidity of the kayak 10 along the length thereof. This frequently leads to kayaks 10 folding across the cockpit area during a broach and pin situation. This structural problem tends to be amplified when the spray skirt 26 is removed and the kayak 10 is allowed to fill with water. Thus, kayakers are frequently forced to keep their spray skirts 26 secured in such situations in order to prevent the kayak 10 from folding and collapsing onto their legs. Exiting a folded kayak 10 is difficult if not impossible without significant force or mechanical advantage. This situation is referred to as “deck entrapment” by whitewater kayakers.
The open cockpit 18 is also disadvantageous as the hull of the kayak 10 is open unless sealed by the skirt 26, creating the potential for rapid flooding and swamping of the kayak which significantly decreases the kayaks buoyancy. Thus, the design of whitewater kayaks 10 results in some significant dangers.
Sit-on-top kayaks 30, as shown in FIG. 2, have been made which have a sealed hull and a generally open seating area in the upper surface 34. The upper surface 34 includes an extensive recess 38 in which a person sits to pilot the kayak 30. The recess 38 typically includes a seat portion 42 and channels for the pilot's legs and feet 46. Thus, in a sit-on-top kayak 30, a significant amount of the upper surface 34 of the kayak is concave where the upper surface of a closed cockpit kayak 10 (FIG. 1) is convex.
Sit-on-top kayaks 30 are typically optimized for flat, calm water (Class I or lower navigation). The hull is watertight for the most part and the user typically sits inside of a depression or recess 38 formed on the deck of the boat which has been designed to act as a seat and foot holds. Further security and control can be provided to the user by the addition of thigh straps which go around the legs of the boater. While the Sit-on-top design addresses some of the problems mentioned above, such as providing easier egress from the kayak, it does not address all of them and presents new ones as well. For example, sit-on-top kayaks are not well suited for whitewater use.
Sit-on-top kayaks 30 have inherent performance problems. The concave nature of the deck 34 acts as a basin and can trap water, decreasing the buoyancy of the kayak until the water can be drained. This draining is usually accomplished by the addition of drain holes in the bottom of the recess 38 (sometimes called a “self-bailing” design). It will be appreciated, however, that even a kayak which drains in seconds can quickly become un-maneuverable on a river where water is coming constantly over the deck, as may be a common situation in whitewater usage. This concavity also adversely affects the resurfacing characteristics of the boat after it has been partially or fully submerged, such as when the boat goes through a hydraulic jump or submerges after landing from a drop.
The deck profile of sit-on-top kayaks 30 also adversely affects the kayaker's ability to self-rescue, which is typically accomplished using a skill known as an “Eskimo Roll” or simply a “roll”. The roll is accomplished when the kayaker positions themselves underwater to pull a stroke perpendicular to the kayak, essentially pulling themselves up from out of the water and back into an upright position. If we imagine a line running through the central axis of a kayak from the bow end to the stern end, we might call this the “long axis” of the kayak. In a conventional kayak, this imaginary “long axis” runs through the body (pelvis) of the kayaker, close to the kayaker's center-of-gravity. In a SOT kayak, this axis runs below the kayaker's body, much further away from the kayaker's center-of-gravity. The closer a kayaker's center-of-gravity is to the long axis of the kayak, the easier the kayak is to roll.
Something similar to this can be observed in figure skating when the skater performs a spin. The closer the skater pulls their limbs in to the axis of their rotation, the faster they spin. Similarly, the more they open up the slower they spin. The lower ability to roll a sit-on-top kayak 30 combined with the relatively insecure seating position, poor water-shedding characteristics, and non-streamlined cross-section profile of the deck make sit-on-top kayaks considerably more difficult to roll than conventional whitewater kayaks.
Finally, the characteristics which make sit-on-top kayaks 30 so easily escapable also make it difficult for the boater to remain seated on the kayak and in control when navigating the violent currents associated with whitewater.
Thus, the concave upper surface 34 of a sit-on-top kayak 30 makes the kayak less maneuverable in certain situations, such as rolling the kayak upright when inverted in the water. Additionally, a person may still hit their head or body on the upper surface 34 of an open kayak 30 if they are tossed about by the water or collisions with rocks.
Some inflatable sit-on-top kayaks have been made in a shape similar to rigid sit-on-top kayaks. These inflatable kayaks, however, are frequently more difficult to navigate as the inflatable hull does not maneuver through the water as crisply as a rigid hull. An inflatable hull is less rigid, and may therefore lose maneuverability as compared to other types of kayaks.
There is thus a need for a kayak which overcomes the limitations of available kayaks. Specifically, there is a need for a kayak which achieves the maneuverability of a rigid closed cockpit kayak without the difficulties and dangers associated therewith. There is need for a kayak which may be more easily mounted and dismounted by a person, which is highly maneuverable in the water, and which reduces the risk of injury caused by a person hitting their head or body on the upper kayak surface while using the kayak.